Build-Depend on libperl5i-perl

Fixing:

| 15:26:56    dh_auto_test
| 15:26:56 Can't locate perl5i/2.pm in @INC (@INC contains: /tmp/buildd/ngcp-schema-1.002+0~20130617132301.4+wheezy~1.gbpf1b505/blib/lib /tmp/buildd/ngcp-schema-1.002+0~20130617132301.4+wheezy~1.gbpf1b505/blib/arch /etc/perl /usr/local/lib/perl/5.14.2 /usr/local/share/perl/5.14.2 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.14 /usr/share/perl/5.14 /usr/local/lib/site_perl .) at /usr/share/perl5/Module/Runtime.pm line 317.
| 15:26:56 BEGIN failed--compilation aborted at t/compile.t line 1.